D. J. Cosgrove, et al. in their article entitled "Isolation of Methoxy- and 2,6-Dimethoxy-p-benzoquinone from Fermented Wheat Germ" Nature, 169, 966 (1952), first reported the isolation of 2,6-dimethoxy-p-benzoquinone (DMQ) from wheat germ.
An Article by R. Pethig, et al. entitled "Ascorbate-quinone interactions: Electrochemical, free radical, and cytotoxic properties" Proc. Natl. Acad. Sci. USA, 80, 129-132 (1983), describes that DMQ in combination with L-ascorbic acid is effective for treating Ehrlich ascites-bearing mice.
The compound DMQ has poor solubility in water and has a certain degree of cytotoxicity. Consequently, it will precipitate from the blood easily and will cause destruction of normal cells, rendering it unsuitable for use as an antitumor agent.
An object of the present invention is to introduce the novel 2,6-dimethoxyhydroquinone-3-mercaptopropionic acid and 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid.
Another object of the present invention is to provide a method for inhibiting tumors in mammal by using 2,6-dimethoxyhydroquinone-3-mercaptopropionic acid or 2,6-dimethoxyhydroquinone-3-mercaptoacetic acid in combination with L-ascorbate or D-isoascorbic acid.